Two-directional dynamic braking circuit



July 21, 1953 s. J. I EsNlAK 2,646,541

TW-DIRECTIONAL DYNAMIC BRAKING CIRCUIT Filed April 11, 1952 Patented July 21,l 1953 oFFIcE TWO-DIRECTONAL DYNAMIC BRAKING CIRCUIT Stanley J. Lesniak, Chicago, Ill.

Application April 11, 1952, Serial No. 281,839

(Cl. S18-368) 4 Claims.

This invention relates to a two-directional braking circuit and more particularly to such a circuit for use with a single series motor which is used to drive ingot buggies.- At the soaking pits the ingot buggies are stopped by plugging the motor. However, when power fails the buggy will drift until the inertia is dissipated and during that period it will be entirely out of control and may do alot of damage.

It is therefore lan object of my invention to provide a two-directional ibraking circuit for the motor which will stop the ingot `buggies from drifting when power to the motor fails for any reason.

VThis and other objects will be more apparent after referring to the following specification and attached drawings, in which:

The single figure shows a schematic wiring diagram of the circuit.

Referring more particularly .to the drawings, the reference numeral 2 indicates a track for an ingot buggy I which is driven by a single series field motor having an armature i5.' rihe power circuit for the motor is shown in heavy lines and the control circuit is shown in light lines. Power is supplied to the motor armature d from power source 8, IG through a switch l2. Power is supplied tothe control circuitl through `a switch I4 and fuse I 6. The control circuit is provided with a master switch I8 having a number of contacts operated by cams whose positions are controlled by the master switch handle. As shown, the masrter switch is provided with four forward and four reversing positions. The switch is provided with contacts 2l), 22 24, 26, 28 and 3i?. When the operator places the master switch handle in the rst position on the forward side the contacts Z and 22 close, this being indicated by the X adjacent the contacts under position I. A relay coil 32 'is connected across the lines 8 and lil through point 34 in the switch i3. A dead-man switch 36 is preferably provided in series with the coil 32 which will be energized as long as the switch 35 is closed. When the coil S2 is energized its contacts 32C will also be closed. A relay coil Sii is arranged in serieswith the contact 32C and a second relay coil 40 is arranged in parallel with the coil 38. When the coil 38 is energized it will operate toggle mechanism #i2 toopen sets of contacts fili and 45. In like manner when the coil 4S is energized it .will operate toggle mechanism iii to open sets of contacts 56 and 52. When the master switch handle is in the iirst position and the switches I2 and I4 closed a relay coil 54 will be energized through contacts 38C and 50C. This of the motor.

will close contacts 555C. Relay coils 5E and 56 will also be energized closing their contacts 5&0, 56C and iC. This closes the power circuit through motor armature t to series eld Si) and starts the car t in its forwardlnovenient. 'The master switch handle is then moved to its second position in which contacts 2:1222 and 2S are closed as indicated by the X adjacent each of these contacts under position 2. Closing of contact 26 energizes relay coil $2 thus closing its contacts 62C and E2C. Closing of contact 52C by-passes resistance d4 thus increasing the speed The master switch handle is then moved to the third position to close contact 28 thus energizing relay coil Et and closing its contacts 66C and 66C. passes resistance $8 to further accelerate the motor. The master switch handle is then moved to its fourth position to energize relay coil 'iQ and close its contacts lEC which Icy-passes resistance l2 and brings the motor rup to full speed. When it is desired to reverse the motor the master switch handle is moved to reversing position numFber one to close contacts 2i] and 2d. Closing of contacts 2t will energize relay coils T4 and i6 thus closing their contacts MC, 'l-SC and 'H3C'. This completes a circuit through the armature S to cause the motor to move in the reverse direction. The master switch handle is then moved to the second reversing position to complete a circuit through coil 62 to by-pass the resistance 6d and thus accelerate the motor. In like manner the master switch handle is moved successively to the third and fourth reversing positions in which relay coils S8 and 'lil are closed to bypass resistances 68 and l2.

A relay coil 'i8 is also connected to the toggle mechanism i2 and when energized will cause the toggle mechanism to close the contacts fili and 46. The relay coil i3 is connected to the motor armature G. A rectifier 80 is provided in this connection and permits flow of current in the direction indicated only. A relay coil 82 is also connected to operate toggle mechanism 48 and when energized will cause contacts 5S yand 52 to close. The relay coil 82 is connected to the motor armature 5 and a rectifier 8H is provided in this connection to permit passageof current only in the direction indicated. The series eld 6B is connected in series with the contacts 52 through lead 8B and is also in series with a resistor 88. Resistor 88 is connected to the motor armature t through a lead 90. The series held Se is also connected in series with the contacts 5@ and a resistor 92. Resistor 92 is connected to the arma- Closing of Contact tiiv hy-v ture 6 through a lead 94'. The series eld 60 is connected through a lead 8S, contacts 46, resistor 92 and the lead S4 to one side of the armature 6 and to the opposite side of armature 6 through contacts 44, resistor 88 and lead Sli. Coils 38 and 4U are suiiiciently powerful to hold their respective contacts open against operation by coils 18 and 82, respectively, prior to dynamic braking operation. When coils 38 and 4E are cle-energized coils 78 and 82 have suicient strength to close their respective contacts.

The operation of the device is as follows: When the power is lost for any reason, such as when the dead-man switch 35 opens or when there is a general power failure, the relay coil 32 will be deenergized thus deenergizing coils 38 and 4D. Progressively, all the other coils Will become deenergized and their contacts will return to their normal position with the exception of contacts 44, 46, 50 and 52 which will be held open by toggle mechanisms 42 and 48. Assuming that the car 3 is moving in a forward position the inertia of the moving car will drive the motor as a generator and set up a counter electromotive force. This will energize relay coil 1B through lead 90, rectifier 80 and lead 94. Relay coil 82 will not be energized because the current will not be able to flow through recier 84. Energization of coil 'i8 will close contacts 44 and 46 thus completing a circuit from the motor armature 6 through series A field 60 and resistors 88 and 92 which will dissipate the power generated. If the car 4 is traveling in the reverse direction the coil 82 will be energized by the counter electromotive force from the motor armature 6 through lead 94, rectifier l 84 and lead 98. In this case coil 18 will not be energized because rectifier 80 will not permit passage of current. Energization of coil 8?. will close contacts 58 and 52 thus completing a circuit through series eld 60 and resistors 88 and 92 which will dissipate the power generated.

While one embodiment of my invention has been shown and described it will be apparent that 4 other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a dynamic braking circuit for a reversible direct current motor having an armature and a series field winding, a i'lrst relay having an opening coil, a closing coil and two sets of contacts, a second relay having an opening coil, a closing coil and two sets of contacts, a rst circuit connected in parallel with said armature, said first circuit including in series a first rectifier and the closing coil of said rst relay, a second circuit connected in parallel with said armature, said second circuit including in series a second rectier and the closing coil or said second relay, said rectiers being oppositely poled with respect to the voltage across said armature, a rst closed series circuit including said rst named contacts, a resistance, said armature and said eld winding, and a second closed series circuit including said second named contacts, said resistance, said armature and said field winding.

2. In a dynamic braking circuit for a reversible direct current motor according to claim 1, a relay having a normally energized coil and normally closed contacts, said normally closed contacts being connected in series with each of said opening coils.

3. In a dyamic braking circuit for a reversible direct current motor according to claim 1, each of said rst and second relays including a toggle mechanism for operating the contacts of said relay, said toggle mechanism being operable by the coils of the relay.

4. In a dynamic braking circuit for a reversible direct current motor according to claim 3, a relay having a normally energized coil and normally closed contacts, said normally closed contacts being connected in series with each of said opening coils.

STANLEY J. LESNIAK.

Y No References Cited. 

